12,770 research outputs found
Systematic study of GaInAs self-assembled quantum wires with different interfacial strain relaxation
A systematic theoretical study of the electronic and optical properties of
GaInAs self-assembled quantum-wires (QWR's) made of short-period
superlattices (SPS) with strain-induced lateral ordering is presented. The
theory is based on the effective bond-orbital model (EBOM) combined with a
valence-force field (VFF) model. Valence-band anisotropy, band mixing, and
effects due to local strain distribution at the atomistic level are all taken
into account. Several structure models with varying degrees of alloy mixing for
lateral modulation are considered. A valence force field model is used to find
the equilibrium atomic positions in the QWR structure by minimizing the lattice
energy. The strain tensor at each atomic (In or Ga) site is then obtained and
included in the calculation of electronic states and optical properties. It is
found that different local arrangement of atoms leads to very different strain
distribution, which in turn alters the optical properties. In particular, we
found that in model structures with thick capping layer the electron and hole
are confined in the Ga-rich region and the optical anisotropy can be reversed
due to the variation of lateral alloying mixing, while for model structures
with thin capping layer the electron and hole are confined in the In-rich
region, and the optical anisotropy is much less sensitive to the lateral alloy
mixing.Comment: 23 pages, and 8 figure
Multi-Stability of Electromagnetically Induced Transparency in Atom-Assisted Optomechanical Cavities
We study how an oscillating mirror affects the electromagnetically induced
transparency (EIT) of an atomic ensemble, which is confined in a gas cell
placed inside a micro-cavity with an oscillating mirror in one end. The
oscillating mirror is modeled as a quantum mechanical harmonic oscillator. The
cavity field acts as a probe light of the EIT system and also produces a light
pressure on the oscillating mirror. The back-action from the mirror to the
cavity field results in several (from one to five) steady-states for this
atom-assisted optomechanical cavity, producing a complex structure in its EIT.
We calculate the susceptibility with respect to the few (from one to three)
stable solutions found here for the equilibrium positions of the oscillating
mirror. We find that the EIT of the atomic ensemble can be significantly
changed by the oscillating mirror, and also that the various steady states of
the mirror have different effects on the EIT.Comment: 10 pages, 9 figure
The Effects of Furosemide and Hypoxia on CIick-Evoked Otoacoustic Emissions in Anesthetized Guinea Pigs
From the concepts of well known ototoxic effects of loop diuretics
and hypoxic state, twenty anesthetized guinea pigs with diuretics and/or hypoxia
were evaluated with click-evoked otoacoustic emissions (CEOAEs) by timesequential
monitoring. Furosemide 25 mg/kg was infused intravenously and
CEOAEs were measured before and 5, 10, 20, 30, 45 and 60 minutes after
injection in 8 guinea pigs. Both echo responses and reproducibilities were
decreased significantly at 10 minutes after injection and showed minimal level at
20 minutes. Recovery of CEOAEs was noted by spectral analysis at 30 minutes
after injection, and full recovery of CEOAEs was evident after then. At 60
minutes after injection, hypoxia of 20 seconds by turning off the artificial
respirator was added. The CEOAEs showed statistically significant decreases
compared with those of prehypoxic state (p<O.OI). The CEOAEs of 8 guinea pigs
with injection of furosemide. 50 mg/kg showed decreased responses and no
fr
recoveries for the 60 minutes observation periods. Findings from this study
support the clinical utility of CEOAEs as a screening test for early detection of
various ototoxicities
Pseudocyst of Temporal Bone and Posterior Cranial Fossa Caused by Cholesterol Granuloma
Accurate preoperative diagnosis of temporal bone lesion is critical because
the surgical approaches used for this region are different depending upon the
specific disease process involved. While CT and MID have improved the accuracy of
preoperative diagnosis of temporal bone pathology, these imaging studies are most
helpful when used in conjuction with one another. This case showed a pseudocyst of
lhe temporal bone and posterior cranial fossa caused by a blockage of aditus ad antrum
due to cholesterol granuloma. The patient was a 33-year-old man with a right-sided
temporo-occipital headache. Computed tomography revealed a mass involving the
temporal bone and posterior cranial fossa with central bony density. On MRI, the mass
showed isosignal intensity with respect to the brain on Tl-weighted image,
hyperintense signal to the brain on T2-weighted image, peripheral enhancement on
gadolinum enhanced image. Histologically, the mass showed a cholesterol cleft,
multinucleated giant cells and a fibrotic capsule without endothelial lining. The patient
had no postoperative difficulty and was discharged without problems
Diversity and distribution of the genus Scrophularia L. (Scrophulariaceae) in Uzbekistan
This article presents a new checklist of Scrophularia in Uzbekistan. The synopsis includes 21 species; one of them is national endemic, and seven species were newly recorded for Uzbekistan as a result of field collecting missions, studies, and examination of Tashkent (TASH), St.-Petersburg (LE), Almaty (AA), and Moscow (MW) herbarium collections. The geographical distribution of Scrophularia in Uzbekistan was mapped and analyzed. The identification key, a table of comparative diagnostic characters, nomenclatural types, and ecological data are provided. (C) 2019 National Science Museum of Korea (NSMK) and Korea National Arboretum (KNA), Publishing Services by Elsevier.Peer reviewe
Properties of Central Caustics in Planetary Microlensing
To maximize the number of planet detections, current microlensing follow-up
observations are focusing on high-magnification events which have a higher
chance of being perturbed by central caustics. In this paper, we investigate
the properties of central caustics and the perturbations induced by them. We
derive analytic expressions of the location, size, and shape of the central
caustic as a function of the star-planet separation, , and the planet/star
mass ratio, , under the planetary perturbative approximation and compare the
results with those based on numerical computations. While it has been known
that the size of the planetary caustic is \propto \sqrt{q}, we find from this
work that the dependence of the size of the central caustic on is linear,
i.e., \propto q, implying that the central caustic shrinks much more rapidly
with the decrease of compared to the planetary caustic. The central-caustic
size depends also on the star-planet separation. If the size of the caustic is
defined as the separation between the two cusps on the star-planet axis
(horizontal width), we find that the dependence of the central-caustic size on
the separation is \propto (s+1/s). While the size of the central caustic
depends both on and q, its shape defined as the vertical/horizontal width
ratio, R_c, is solely dependent on the planetary separation and we derive an
analytic relation between R_c and s. Due to the smaller size of the central
caustic combined with much more rapid decrease of its size with the decrease of
q, the effect of finite source size on the perturbation induced by the central
caustic is much more severe than the effect on the perturbation induced by the
planetary caustic. Abridged.Comment: 5 pages, 4 figures, ApJ accepte
A Novel Meatoplasty Method in Canal Wall Down Tympanomastoidectomy: A Perichondrial Posterior Fixation Technique
ObjectivesAlthough it is well recognized that a small meatus after canal wall down (CWD) tympanomastoidectomy can cause a lifetime problem, unsatisfactory results are frequently encountered. We herein introduce a novel technique, perichondrial posterior fixation (PPF), to maintain a wide external auditory canal (EAC), to minimize postoperative wound infection due to the smaller dead space and to improve the posterior auricular cosmetic outcome.MethodsA total of 73 patients who underwent CWD tympanomastoidectomy were included. Interventions are CWD tympanomastoidectomy with the PPF technique. Review of the medical records and evaluation of the postoperative size of the meatus and the extent of the cavum conchal cartilage buried within the mastoid cavity by taking digital photographs.ResultsThirty males and 43 females were included and the mean age was 44.1 yr (range, 6 to 66 yr). The mean follow-up duration was 26 months (range, 12 to 56 months). All ears maintained a clean and large external meatus. The posterior auricular cavum conchal cartilage was successfully prevented from being buried into the mastoid cavity in all ears. The extent of cartilage buried into the mastoid cavity was much reduced compared to the conventional technique.ConclusionThe PPF technique, which is a novel meatoplasty technique in CWD tympanomastoidectomy, seems to be effective in maintaining a large external meatus and improving the cosmetic outcome with minimal risk of complications
Intracellular interferons in fish : a unique means to combat viral infection
Peer reviewedPublisher PD
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